To me, this sounds like a boondoggle for bureaucratic "planners". There are so many different types of missions that having a plan in place for a "rescue" is going to be mission-specific and not even possible for all phases of a mission.
We already have safety abort equipment for the ascent phase of crewed space flights. And, there is nothing we can do when something goes wrong during the descent phase. Even the Apollo 13 problem, where the capsule needed to go around the Moon to head back, and was coming back too fast for any sort of rescue rendezvous on the return trajectory. has no chance for some sort of rescue craft taking off from Earth and getting the crew from the malfunctioning capsule transferred to a rescue craft.
So, the situations that seem feasible would be the "stuck in orbit" and maybe "stuck on the Moon" situations. Even "stuck on Mars" is not likely to be resolved by a rescue unless the crew has a lot of extra subsistence capability to tide it over for the long rescue trip to arrive.
The ISS already has a "lifeboat" type policy that enough capsules need to be docked to take all crew members back to Earth. So, unless there is problem with both a capsule and the ISS at the same time, we already have the "rescue" capability in the form of Soyuz and Dragon capsules that can be launched from Earth while the ISS is used as refuge until they arrive.
So, if there really is a scenario that can be solved by a rescue craft, it seems that is when a capsule is stuck in orbit and not able to reach the ISS or safely deorbit and reenter. The capsules are supposed to have fairly long life-in-orbit capability, but it is possible to have some sort of event that could damage that as well as the propulsion capability. In those cases, another capsule would be able to do a rescue if (1) it is ready to launch in time, and (2) it has compatible docking capability with the capsule in trouble.
So, does that mean that every launch to orbit would require a quick-launch capable rescue vehicle to be ready on a pad, somewhere? Considering the timing of launch "windows" to specific orbits, would it require more than one rescue craft standing by at different parts of the globe? That is starting to sound expensive.
And, considering the number of times that rescue was needed and technologically could have been accomplished, it seems that there is not much call for rescue to justify the costs of always being ready.
But, on the other hand, if this is aimed at some expectation that there will be myriads of launches of space tourists and industrial workers in the future, that would seem to suggest that there would probably be some vehicle about ready to launch most of the time. Changing the flight plan to become a rescue mission would not be as much of an expense as having a stand-by at all times that is almost never used.
So, if the planning is limited to standardizing docking hardware and space suit compatibility with all space craft, that would be a plus. And if there was an agency that would pay a commercial company to perform a rescue with whatever craft were available at the time of need, that seems workable and useful.
But, if this turns into a government mandate that a standby rescue craft is required to get a launch permit for every launch, then this would become a real millstone around the neck of the commercial space industry.
And, what would FAA do if there was a "mishap" on a crewed Falcon 9 launch and the rescue vehicle was another Falcon 9?